Impulse Noise

The term noise usually describes undesirable disturbances or fluctuations and is considered to be the worst case for communication and error-free information transmission and processing in engineering. The noises you hear throughout the day can be either continuous noise, intermittent noise, impulsive noise, or low-frequency noise.

In this article, we will go through the definition of impulse noise, its types, models, examples, differences or comparisons with typical noise, applications, techniques or algorithms to measure, advantages, disadvantages, conclusion and FAQs.

What is Impulse Noise?

Impulse noise is one of the noise types that carries sudden sharp sounds or sudden bangs of short duration. To put it simply, the warning note popping up or message indication sounds while using the devices. It is characterized by its short duration and high amplitude, often appearing as isolated pulses within the signal. Impulse noise can be caused by various factors such as electrical interference, voltage spikes, or physical disturbances in a transmission medium.

Impulse Noise Image Pattern

Types of Impulse Noise

There are three types of impulse noise that includes,

1. High pulse sound
2. High energy impulse sound
3. Typical impulse sound

High Pulse Sound

High impulse sounds are characterized by their sudden onset and high intensity. The short-duration bursts of sound with high energy levels, often causing a startling effect due to their abruptness and loudness.

High Energy Impulse Sound

High energy impulse sounds typically involve even greater levels of energy release. These sounds are not only loud but also involve the rapid release of immense energy, resulting in intense pressure waves that can cause physical damage to nearby structures or pose risks to human safety, especially in close proximity to the source.

Typical Impulse Sound

Typical impulse sounds are everyday occurrences characterized by their sudden, transient nature. It produce short-lived bursts of sound with moderate intensity and can be disruptive and annoying, especially in residential or office environments. However, they generally pose minimal risk to hearing health or physical safety compared to others.

Models of Impulse Noise

There are basically two models of Impulse Noise given below :

1. Salt Impulse Noise
2. Pepper Impulse Noise

Salt Impulse Noise : We can assume it is observed by the brightest gray level in the image by the visibility of white spot in the image.

Pepper Impulse Noise : We can assume it is observed by the darkest gray level in the image by the visibility of black spot in the image.

Examples of Impulse Noise

• Gunshots are a classic example of high impulse sounds. Other examples include hammering of metal or wood, falling hammer, etc.
• The launch of rockets or other explosive events and fireworks are examples of high energy impulse sound.
• Slamming the door, back-up alarms, whistles, horns, bells, sirens, hammering, dogs barking etc.. comes under typical impulse sounds.

Difference Between Noise and Impulse Noise

Noise	Impulse Noise
Continuous fluctuations or disturbances in the signal over time	It is non continuous irregular pulses for short duration
The amplitude peaks are normal	Characterized by high amplitude peaks
Considered as enemy for technology in data gathering and processing	One of the noise types that has high effect on producing errors

Applications of Impulse Noise

They are inevitable occurrences in various technologies such as

• Signal processing
• Image processing
• Communications
• Electronics

Signal Processing

In signal processing, impulse noise appears as sudden spikes or disturbances in the signal waveform. The signal is the meaningful information that you’re actually trying to detect. The noise is the random, unwanted variation or fluctuation that interferes with the signal.

Image Processing

Impulse noise usually corrupts images due to a defect in the device’s hardware or in the camera’s sensor. Impulse noise replaces some of the pixels in the original image. The salt-and-pepper noise, which takes only one of the following two values [0,55] and random white dots in the image are the effects of impulse noise occurs during image acquisition and transmission.

Communications

In communications systems, impulse noise can be caused by positioning a communication cable near a source of intermittent but strong electromagnetic pulses, such as an elevator motor. It degrades telephony only marginally, if at all, but can seriously corrupt data transmissions.

Electronics

In electronics, impulse noise originates from various sources such as electromagnetic interference, voltage spikes, or device malfunctions. These noise can disrupt the operation of electronic circuits, causing errors in control systems.

Techniques and Algorithms to Tackle Impulse Noise

• The most preferred Median, adaptive and bilateral filtering technique.
• Wavelet denoising for reconstructing the denoised signal.
• Algorithms as Least Median of Squares or Least Trimmed Squares (LTS) estimator are statistical techniques used to estimate signal parameters in the presence of outliers, such as impulse noise.
• Error correction codes such as Reed-Solomon codes or convolutional codes are used to detect and correct errors introduced by impulse noise during data transmission.
• Also to suppress the impulse noise, the threshold value is adaptively adjusted.

Sample Impulse Noise Image

The picture shows the pitch vs time graph where sudden pitch value gathered in between smooth recording signals.

time(x axis) vs pitch(y axis)

Advantages and Disadvantages of Impulse Noise

Here are some Advantages and Disadvantages of Impulse Noise given below :

Advantages

Though mostly impulse noise is considered as an utter disturbance in most technological contexts, still it is being used in various testing stages as pulse testing and stress testing where impulse noise is intentionally introduced to assess the robustness or resilience of a system by evaluating how well a system can handle sudden disturbances and recover from them.

Disadvantages

• Impulse noise results in greater error rates at higher data rates
• It is difficult to extract required signal from impulse noise than other noises

Conclusion

Overall, tackling impulse noise is considered as a challenge for engineers across a wide range of technological and practical domains and also impulse noise can pose safety risks due to its potential to cause equipment malfunction, communication failures, or physical damage.

Addressing these challenges, this requires the development and implementation of effective mitigation strategies, including signal processing techniques, noise reduction methods, and engineering controls, to ensure the reliability, safety, and performance of systems and applications.

Impulse Noise – FAQs

How is noise used in brain study ?

Within the auditory system, recent studies suggest that intrinsic noise plays a key role in signal processing and might even correspond to increased spontaneous neuronal firing rates observed in early processing stages of the auditory brain stem and cortex after hearing loss.

How impulse noise is handled in signal processing?

Techniques like median filtering, adaptive filtering, or robust statistical estimation are used to mitigate the effects of impulse noise in signal processing applications.

What are the effects of impulse noise in humans?

In acoustics, high levels of impulse noise (200+ decibels) may damage internal organs, while 180 decibels are enough to damage human ears.

What are the possible variation in impulse noise?

High frequency impulse noise energy can cause bad voice quality, pixel loss and degrade or freeze the top video services like Netflix. Digital Subscriber Line/Loop (DSL) services are affected differently by repetitive electrical impulse noise (REIN), prolonged electrical impulse noise (PEIN), short impulse noise event (SHINE) and electromagnetic interference (EMI).